[论文解读] Hybrid integrated near UV lasers using the deep-UV Al2O3 platform

Cornelis A. A. Franken, W. A. P. M. Hendriks+10 more|arXiv (Cornell University)|Feb 22, 2023

Photonic and Optical Devices被引用 19

一句话总结

Direct translation of tldr into Chinese is provided below.

ABSTRACT

Hybrid integrated diode lasers have so far been realized using silicon, polymer, and silicon nitride (Si3N4) waveguide platforms for extending on-chip tunable light engines from the infrared throughout the visible range. Here we demonstrate the first hybrid integrated laser using the aluminum oxide (Al2O3) deep-UV capable waveguide platform. By permanently coupling low-loss Al2O3 frequency-tunable Vernier feedback circuits with GaN double-pass amplifiers in a hermetically sealed housing, we demonstrate the first extended cavity diode laser (ECDL) in the near UV. The laser shows a maximum fiber-coupled output power of 0.74 mW, corresponding to about 3.5 mW on chip, and tunes more than 4.4 nm in wavelength from 408.1 nm to 403.7 nm. Integrating stable, single-mode and tunable lasers into a deep-UV platform opens a new path for chip-integrated photonic applications.

研究动机与目标

• Demonstrate a chip-scale hybrid integrated diode laser in the deep-UV using an Al2O3 platform.
• Couple a GaN/InGaN double-pass amplifier to Al2O3 feedback circuits for tunable, single-wavelength operation.
• Achieve hermetically sealed packaging and UV-compatible bonding for long-term stability.
• Characterize waveguide losses, coupling, and Vernier filter performance to enable single-mode, tunable UV output.

提出的方法

• Fabricate Al2O3 cores embedded in SiO2 cladding to provide tightly guided single-mode UV propagation.
• Design and fabricate sequential Al2O3 microring resonators in a Vernier configuration for frequency-selective feedback.
• Integrate a 405 nm InGaN/GaN double-pass amplifier with the Al2O3 feedback chip through UV-compatible bonding.
• Implement thermo-optic microheaters for tuning phase and coupling in the Vernier filter and output coupler.
• Pack the amplifier and feedback chip in a hermetically sealed butterfly package with a gas environment (nitrogen/argon) for stability.
• Characterize propagation loss, coupling, and Vernier filter transmission to set optimal coupling (κ^2) and Q-factors.

实验结果

研究问题

• RQ1 Can the deep-UV Al2O3 platform support stable, tunable hybrid integrated lasers when coupled with a UV GaN/inGaN amplifier?
• RQ2 What are the achievable output power, tuning range, spectral purity (SMSR), and coherence/linewidth in this platform?
• RQ3 How do propagation losses, coupling, and Vernier filter design affect laser performance and stability in the near-UV?
• RQ4 What packaging and hermetic sealing requirements are necessary for long-term UV operation?

主要发现

• Maximum fiber-coupled output power of 0.74 ± 0.04 mW (≈3.5 ± 0.5 mW on-chip).
• Tuning of the laser exceeding 4.4 nm from 408.1 to 403.7 nm.
• Single-wavelength operation with SMSR of 42–43 dB under different κ^2 settings.
• Laser operates without mode hops for at least 84 minutes, with drift below 1.6 GHz and final stabilization within tens of MHz.
• Coherence time inferred as ≈-based on a delayed self-heterodyne measurement indicating linewidth around 25 MHz or lower.
• Propagation losses in Al2O3 waveguides measured at 2.8 ± 0.3 dB/cm; chip-to-fiber coupling loss ~10.2 ± 0.8 dB/facet.